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Epidemiology SJSM > block 2 quiz/exam > Flashcards

block 2 quiz/exam Flashcards

1
Q

Primordial

A

The goal is to stop/reduce immergence of disease (Tabacco tax laws)

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2
Q

Primary

A

Control risks via vaccines & safe water etc

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3
Q

Secondary

A

Early detection (screening like mammograms, BP/BS testing)

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4
Q

Tertiary

A

Reduce complications associated with disease (rehab and better treatment)

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5
Q

Equation for infectivity

A

Infected
/
Exposed

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6
Q

Equation for virulence

A

Ill
/
Infected

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7
Q

Equation of pathogenicity

A

Ill
/
Exposed

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8
Q

Describe categorical/qualitative nominal

A

Things that can’t be ordered like gender/blood group/married status

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9
Q

Describe categorical/qualitative ORDINAL

A

Things that can be in ordered categories (smoker/non-smoker/ex-smoker, stage of disease, & pain scale)

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10
Q

Describe numerical/quantitative DISCRETE

A

Numerical values you can count i.e number of days sick from work

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11
Q

Describe numerical/quantitative CONTINUOUS

A

Numerical ranges Height, weight, age etc

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12
Q

Equation for case fatality rate

A

of deaths due to disease
/
# of disease cases

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13
Q

Equation for 5 yr survival rate

A

patients alive @ the END of 5yrs
/
# patients alive @ START of 5yrs

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14
Q

Equation for Relative survival rate

A

Observed # of plp alive with disease
/
expected # survival if they didn’t have disease

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15
Q

Sensitivity describes

A

people with disease

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16
Q

Specificity describes

A

disease-free people

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17
Q

PPV Positive-predictive value

A

People have the disease with a positive test

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18
Q

NPV Negative predictive value

A

People that don’t have the disease with a negative test

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19
Q

Describe a True positive

A

Has the disease & a positive test (pregnant lady + positive preggo test)

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20
Q

Describe a True negative

A

No disease with a negative test (Man with negative preggo test)

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21
Q

Describe a false positive

A

No disease with a positive test
(man with a positive preggo test)

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22
Q

Describe a false negative

A

Disease with a negative test (pregnant lady with a negative preggo test)

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23
Q

Sensitivity equation

A

TP
/
(TP+FN)

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24
Q

Equation for specificity

A

TN
/
(FP+TN)

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25
Q

Equation for PPV

A

TP
/
(TP+FP)

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26
Q

Equation for NPV

A

TN
/
(TN+ FN)

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27
Q

Equation for accuracy

A

TP + FP
/
ALL

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28
Q

Equation for prevalence

A

TP +FN
/
ALL

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29
Q

Low threshold indicates what?

A

high sensitivity and FP’s (aka low specificity)

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30
Q

High threshold indicates what?

A

high specificity and FN’s (aka low sensitivity)

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31
Q

Botulism is a ____ category disease

A

A

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32
Q

Brucellosis is a ______ category disease

A

B

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33
Q

Anthrax is a ______ category disease

A

A

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34
Q

Nipah virus is a ______ category disease

A

C

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35
Q

H2N2 is a ______ category disease

A

C

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36
Q

Bubonic plague is a ______ category disease

A

A

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37
Q

Tularemia is a ______ category disease

A

A

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38
Q

Q. fever is a ______ category disease

A

B

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39
Q

SARS is a ______ category disease

A

C

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40
Q

Small pox is a ______ category disease

A

A

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41
Q

Hemin fever is a ______ category disease

A

A

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42
Q

Staphylococcal infections are a ______ category disease

A

B

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43
Q

Hanta virus is a ______ category disease

A

C

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44
Q

Racin toxin is a ______ category disease

A

B

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45
Q

Typhus is a ______ category disease

A

B

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46
Q

Psittaeosis is a ______ category disease

A

B

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47
Q

Study types:

Ecological

A

Compares people in different places at the same time
A study that assesses links between an exposure and an outcome usually in larger populations (countries etc)

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48
Q

Study types:

Cohort study

A

Study involves a group with common characteristics (exposed vs unexposed) over a period of time

Prospective (looking forward happens before the groups develop an outcome

Retrospective (looking backwards) happens after the exposed group has developed an outcome

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49
Q

Study types:

Case control

A

2 groups (exposed vs control) to find if exposed are associated with an outcome (i.e is a risk factor ass with developing a disease)

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50
Q

A group of patients with histologically confirmed cervical cancer (cases) is compared to otherwise similar patients without histologically confirmed cervical cancer (controls) for the presence of human papillomavirus (exposure).

A

Case control

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51
Q

Determining the incidence of cholera deaths in different parts of a city to identify the source of exposure

A

Ecological study

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52
Q

Investigating the number of patients with both coronary heart disease and hypertension in the year 1998

A

Cross-sectional study

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53
Q

Study types:

Cross-sectional

A

Determines the prevalence of exposure and disease at a specific point in time

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54
Q

Individuals with a smoking history of ≥ 1 pack of cigarettes a day (exposed group) are compared to individuals who are nonsmokers to see if there is a difference in the proportion of patients in each group that develop lung cancer (e.g., the outcome) within a specific follow-up period.

A

Prospective cohort study

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55
Q

Individuals with a smoking history of ≥ 1 pack of cigarettes a day (exposed group) 5 years ago are compared to individuals who were nonsmokers 5 years ago to see if there is a difference in the proportion of patients in each group that eventually developed lung cancer (outcome) within a specific follow-up period.

A

Retrospective cohort study

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56
Q

Study types:

Randomized control trial

A

determine the possible effect of a specific intervention on a given population

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57
Q

Study types:

Randomized cluster trial

A

an experimental study design in which the unit of randomization is a group rather than an individual participant

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58
Q

Study types:

Field trials

A

to determine the effect of disease prevention interventions in individuals who do not already have a disease

59
Q

Study types:

Community trials

A

similar to field trials, but follow communities rather than individuals

60
Q

observation of children who did and did not receive the Salk vaccine for prevention of poliomyelitis to see whether they developed paralysis or death

A

Field trial study

61
Q

studying the incidence of myocardial infarction and stroke in communities who implement lifestyle changes to prevent cardiovascular disease compared to communities who do not implement such changes

A

Community trial study

62
Q

Describe Random error

A

Definition: an error that occurs due to chance and/or limitations of precision

63
Q

How can random error be limited?

A

It can be reduced by repeated measurements and averaging over a large number of observations

  • Increasing sample
  • Assessing statistical significance
64
Q

Describe Systematic error

A

An error in the study design or the way in which the study is conducted that causes systematic deviation of findings from the true value

65
Q

Selection bias

A

The individuals in the sample group are not representative of the population from which the sample is drawn because the sampling or the treatment allocation is not random

66
Q

Sampling bias (ascertainment bias)

A

Occurs when certain individuals are more likely to be selected for a study group, resulting in a nonrandom sample
This can lead to incorrect conclusions being drawn about the relationship between exposures and outcomes.
Limits generalizability

67
Q

Healthy worker effect:

A

The working population is healthier on average than the general population The working population is healthier on average than the general population

68
Q

Volunteer bias

A

Individuals who volunteer to participate in a study have different characteristics than the general population.

69
Q

Survival bias (prevalence-incidence bias or Neyman bias)

A

Happens when the observed subjects have a more or less severe case of disease compared to the standard individual exposed

Note if the people with severe disease die before observation then it means people with milder disease will be observed
&
if people with the milder disease resolves before observation then those with the more severe strain will be reported

70
Q

Survivor bias is most common in which 2 studies

A

cross-sectional and case control

71
Q

Measurement bias

A

any systematic error that occurs when measuring the exposure or outcome

72
Q

Observer bias (experimenter-expectancy effect or Pygmalion effect)

A

The measurement of a variable or classification of subjects is influenced by the researcher’s knowledge or expectations.

73
Q

Reporting bias

A

a distortion of the information from research due to the selective disclosure or suppression of information by the individuals involved in the study
Can involve the study, design, analysis, and/or findings
Results in underreporting or overreporting of exposure or outcome

74
Q

Recall bias

A

awareness of a health condition by subjects means they might recall more related risk factors associated with their condition (recall a certain exposure)
Common in retrospective studies

75
Q

After claims that the MMR vaccine caused autism became public, parents of children diagnosed with autism were more likely to recall the start of autism being soon after their child was vaccinated, as compared with parents of children who were diagnosed with autism prior to these claims becoming public.

A

Recall bias

76
Q

Attrition bias

A

A type of nonresponse bias
Selective loss of participants to follow up
Most commonly seen in prospective studies
Risk that the remaining participants differ systematically from those lost to follow up

77
Q

Lend time bias

A

A type of bias in which survival time is overestimated because of early diagnosis through screening and does not reflect an actual delay in mortality

This happens when survival times are chosen as an endpoint of screening trials.

78
Q

Lead time is described as

A

the length of time between the initial detection of disease and the expected outcome (i.e., death or onset of clinical symptoms)

79
Q

Central tendency bias

A

measures to describe a common, typical value of a data set (e.g., clustering of data at a specific value)

80
Q

Misclassification bias

A

an error in which research subjects are classified into the wrong exposure or outcome groups, thereby distorting the observed association

81
Q

In a study on risk factors for lifetime cancer diagnosis, participants are asked if they have ever been exposed to radiation but are not asked for further clarification (e.g., what type, how recently, for how long). This leads to an incorrect conclusion about the association between radiation exposure and lifetime cancer diagnosis. Because all participants were asked the same vague question, the frequency of classification errors is similar across exposed and unexposed groups.

A

Misclassification bias

82
Q

actions that address environmental, socioeconomic, and behavioral risk factors that affect a population as a whole to prevent potential disease or injury.

A

primordial prevention

83
Q

Programs on food safety and nutrition guidelines

A

Primordial

84
Q

Campaigns discouraging tobacco and drug use (e.g., smoke-free air laws in public buildings)

A

primordial

85
Q

Building bicycle and sidewalks to promote physical activity

A

primordial

86
Q

actions targeted at preventing specific diseases from occurring to decrease the incidence and, subsequently, the prevalence of those diseases

A

Primary

87
Q

Immunization

A

Primary

88
Q

Lifestyle modification (e.g., smoking cessation to reduce lung cancer risk, exercise to reduce the risk of heart disease, dental care to reduce the risk of tooth loss)

A

Primary

89
Q

Fortification of salt with iodine to prevent iodine deficiency
Fluoridation of toothpaste, water, and salt to reduce the risk of dental conditions

A

primary

90
Q

Fortification of food with folic acid to reduce the prevalence of neural tube defects

A

primary

91
Q

Health legislation (e.g., seat belt laws, food safety standards, traffic laws)

A

primary

92
Q

Ocular prophylaxis for all newborns to prevent neonatal gonococcal conjunctivitis

A

primary

93
Q

actions targeted at early detection of disease in asymptomatic patients (or while the symptoms of the condition are still mild) to promote early intervention

A

Secondary

94
Q

actions taken to optimize care of patients with an existing disease to improve well-being and prevent complications

A

tertiary

95
Q

Adjuvant therapy (e.g., tamoxifen in breast cancer) to reduce risk of cancer recurrence

A

tertiary

96
Q

Blood pressure management (e.g., antihypertensives) to decrease risk of a cardiovascular event

A

PRIMARY

97
Q

Diabetes management (e.g., antidiabetic medication

A

tertiary

98
Q

HbA1c monitoring) to decrease risk of chronic kidney disease and/or cardiovascular events

A

tertiary

99
Q

Measures to prevent restenosis following myocardial infarction (e.g., low-dose aspirin)

A

tertiary

100
Q

Categorical variable (nominal variable):

A

variables that have a finite number of categories that may not have an intrinsic logical order

101
Q

Continuous variable (nondiscrete variable):

A

variables that can assume any real number value

102
Q

Discrete variable

A

Discrete variable: variables that can only assume whole number values

103
Q

Variable scales
Definition:

A

types of measurement scales (categorized as categorical scales and metric scales

104
Q

Categorical scale (qualitative)

A

The distance (interval) between two categories is undefined.
Includes the nominal scale and ordinal scale

105
Q

Metric scale (quantitative)

A

The distance between two categories is defined and the data can be ranked .
Includes the interval scale and ratio scale

106
Q

a researcher examined the rates of lung cancer in different countries and the levels of cigarette consumption in those countries. The study compares the frequency of lung cancer and the frequency of cigarette use across the populations of different countries. This study could be used to investigate whether smoking rates impact the occurrence of lung cancer at a population level.

What is the study type and it’s limitation

A

Ecological study
&
The results of this study cannot be directly applied to individuals, as they only apply to population-level data and cannot account for individual differences in risk factors. (Ecological fallacy)

107
Q

A study between the link smoking and lung cancer. We select a group of 10,000 people aged 50-75, who are lifelong smokers, and track them for 10 years. We compare this group against another 10,000 people aged 50-75 who have never smoked. We then observe the incidence of lung cancer in both groups over the 10-year period and compare the results.

What is the study?

A

Prospective Cohort study

108
Q

Describe what an ecological study is?

A

A study that looks at how often a disease occurs and how often a certain risk factor is present in different groups of people (population)

109
Q

Describe an ecological fallacy

A

Applying the results of an ecological study to the individual members within that population.

The results of an ecological study are only relevant to the group/pop as a whole

110
Q

Describe a cohort study

A

A study that compares two groups. One with a risk factor/exposure & one without (control) to see i the risk factor/exposure is linked to the development of a disease

It can be forward looking (prospective) aka follows people over time
Or
Can be backward-looking (retrospective) aka looks at medical records & history

111
Q

we want to investigate the link between a certain chemical exposure and cancer of the bladder. We select a group of 100 people who have been diagnosed with bladder cancer and 100 people who do not have the disease. We then look back at their medical records to see if they had any prior exposure to the chemical in question. By comparing the exposure rates of both groups, we can determine if there is an association or correlation between the exposure and the development of the disease. The study asks the question of what happened, trying to find out if prior exposure to the chemical led to the development of the disease

What is the appropriate study type to use?

A

Case-control study

112
Q

Describe a case-control study

A

A retrospective study looks t groups of people and compares people who have a disease vs people that don’t to determine if there is a risk

uses odds ratio

113
Q

describe the odds ratio

A

It looks at whether the odds of being exposed to a risk factor are different between the groups and if the contributes to disease

ex.Patients with COPD had higher odds of a
smoking history than those without COPD

114
Q

Describe a cross-sectional study

A

A study that looks at the frequency of a disease and the frequency of risk-related factors in the population at a present time

“find out what’s happening now in terms of prevalence and risk factors”

114
Q

we want to investigate the prevalence of obesity and the frequency of certain risk factors for obesity, such as lack of exercise and unhealthy eating habits. We survey 1000 randomly selected individuals and collect data on their height, weight, exercise habits, and eating habits. We can then use this data to determine the frequency of obesity and the frequency of the risk factors in our population sample

What is the appropriate study type?

A

cross-sectional

115
Q

a cross-sectional study specifically measures what variable?

A

disease prevalence

116
Q

a cohort study specifically measures what variable?

A

Disease incidence

117
Q

we want to investigate whether a particular drug is effective in treating a particular type of cancer. We select ten patients who have been diagnosed with the same type of cancer and have been treated with the drug. We then describe the experiences of each patient, including their diagnosis, treatment, and outcome. By looking at the similarities and differences between these cases, we can learn more about the effectiveness of the drug for this particular type of cancer.

What study type does this describe?

A

Case-series

118
Q

Describe case series

A

A study that looks at patients with similar experiences (diagnosis, treatment, or outcome) and analyses their outcomes

119
Q

, if researchers are studying the relationship between a particular illness and exposure to a certain chemical, they may ask people who have the illness to recall their previous exposure to the chemical. However, if the people being asked already know that the chemical is being studied for its link to the illness, they may think more about whether they were exposed to it than they would have if they didn’t know this. This affects the reliability of the study results because it cannot be sure whether the reported exposure is accurate or not.

This describes what type of bias?

A

Recall bias

120
Q

Describe the recall bias

A

When people know they have a disorder, they may recall things differently than those that don’t know when asked in a study

121
Q

Describe selection bias

A

not randomly selecting individuals for a sample or allocating treatment groups, it doesn’t represent the actual population

122
Q

Describe Berkson bias

A

aka the bedside bias. Researcher choose cases/controls from the hospital who tend to be less healthy and have different exposures than the actual population

123
Q

Describe the attrition bias

A

Participants lost before follow up have different prognoses to those who complete the study

124
Q

if a study is conducted on a particular population, but only a certain group of people are surveyed, the information collected may be systematically distorted because the views of the people who were not surveyed are not reflected in the results. Similarly, if information is collected using biased questions or questions that only focus on certain aspects of a topic, this can also lead to systematic distortion

this describes what type of bias?

A

Measurement bias

125
Q

Describe measurement bias

A

Information is gathered in a way that is inaccurate or biased it can be due to a number of factors including the Hawthorne effect

126
Q

Describe the Hawthorne effect

A

participants
change behavior upon
awareness of being observed

127
Q

Describe the lead-time bias

A

when a disease is detected early, it is often thought that this leads to a better chance of survival even though the course of the disease hasn’t changed

128
Q

Describe the features of the figure

A

Normal distribution:
The best measure of central tendency where mean=median=mode are all equal

129
Q

Describe the figure

A

Negative skew:
Longer tail to the left
mean<median<mode

130
Q

Describe the figure

A

Positive skew:
Longer right tail
mode>median>mean

131
Q

Describe the following figure

A

Bimodal:
Suggests two different populations

132
Q

Describe the mean

A

It’s MOST affected by outliers

Sum of all values
/
total number of values

133
Q

Describe median

A

The middle value of an odd set and the average between the two middle numbers of an even set

134
Q

Describe the mode

A

The most common value in the set
It’s the LEAST affected by outliers

135
Q

Calculate the median survival times for line A & B

A

A 3
B 8

136
Q

A standard urine test used to detect cocaine has a sensitivity of 97%, a specificity of 94%, a positive predictive value of 90%, and a negative predictive value of 95%. Recent data suggest that the use of cocaine in all age groups has declined since the screening test properties were determined. A decline in cocaine usage will most likely have which of the following impacts on the results of this screening test?

A

Increase the negative predictive value

137
Q

A test is used in 50 people with disease and 50 people without. These are the results:

A

fill in the table

138
Q

Describe the addition rule

A

If two events (A&B) can’t happen at the same time i.e rolling a 3 & 5 on dice, then the probability of them happening is equal to the sum of their INDIVIDUAL probabilities

ex. roll a 2 & 6 (1/6 chance for either) 1/6+1/6 = 2/6 or 1/3

139
Q

Describe the multiplication rule

A

If 2 events (A&B) are independent of each other (one occurring doesn’t effect the other) then the probability of both happening is equal to the product of their original probabilities

ex. rolling a 6 (1/6) & flipping heads on a coin (1/2); 1/6*1/2 = 1/12

140
Q

precision

A

Test precision in epidemiology refers to how accurately a diagnostic test or screening tool can detect the presence or absence of a specific disease or condition. In simpler terms, it is a measure of how well the test can correctly identify whether someone has a particular disease or not. A highly precise test will have a low rate of false positives (incorrectly classifying someone as having the disease when they do not) and false negatives (failing to identify someone as having the disease when they actually do)

141
Q

Accuracy

A

In epidemiology, test accuracy refers to how well a medical test can correctly identify or rule out a particular condition or disease

test with high accuracy will have a low number of false positives (healthy people wrongly identified as having the condition) and false negatives (sick people wrongly identified as not having the condition).

142
Q

Validity

A

it measures whether a test can correctly identify people with a disease or condition and exclude people who do not have the disease or condition. A valid test is important in epidemiology because if a test is not reliable, the results and conclusions that are based on that test may be misleading or inaccurate. To determine the validity of a test, researchers compare the results of the test with a gold standard diagnostic tool to assess its accuracy

Epidemiology SJSM (5 decks)

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